Maico

Every Twin Air filter is constructed from two layers of open-pore foam that are bonded together to provide maximum filtration and superior airflow. A coarse-foam outer shell is flame laminated with a fine-foam inner core, resulting in a one-piece design that is both functional and durable.

Will fit the following models:
1980 1981 Maico 250 440 490 Clamp On Twin Air Filter

Does not use the stock air boot. Can sit inside the stock airbox. 63mm ID on the air boot.